Very thin hair with hair fall n dandruff

I am having dandruff ,oily scalp but dry ends, my hair never really grow faster,it's very low in density and very thin,prone to more split ends,however I use good shampoo,proper oiling I do twice a week, not expose my hair too much in sun . Having really bad dandruff,in my city water is red, more in arsenic and hard ,I used purified water on hair,but then also my hair is prone to breakage. I am having pcod as well, but not on Any medication for it , I am having acne scars, but it's medicine is also about to over,do basically currently I am not on any such medication.. kindly help me maintain my thin hair, oily at scalp ,dry at ends,and hair fall is the major issue as I have dandruff as well. Suggest me good shampoo,medicine, and anything you want .. thank you soo much in advance doctor. Believe me I am having very thin hair... Help me... Thank you.